Phase Change Material for Vapor-Based Polyester Textile Decolorization
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Solution Overview
Problem
Conventional vapor-based decolorization techniques for polyester textiles face issues of low decolorization rate and uneven decolorization when processing large amounts due to resistance from stacked textiles, leading to insufficient vapor penetration.
Innovation Solution
Incorporating a phase change material with a phase change temperature lower than the vapor temperature of the decolorizing agent into the polyester textiles, which creates a local temperature difference to guide vapor penetration and ensure sufficient contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the amount of discarded polyester textiles is increased for processing, then the productivity is improved, but the vapor penetration ability deteriorates due to increased stacking thickness and resistance
Solution Approach 1:
The patent utilizes the phase transition of water (liquid to vapor) during steam decolorization. The steam penetrates the stacked polyester textiles and transfers heat through condensation and evaporation cycles, creating internal temperature differences that facilitate vapor penetration deep into the stack without requiring increased stacking thickness or pressure.
Solution Approach 2:
The patent exploits thermal expansion and contraction of the polyester textiles during steam exposure. The repeated heating and cooling cycles cause the textile structure to expand and contract, creating channels and reducing resistance to vapor penetration, thereby maintaining effective decolorization even at high processing capacities.
2Productivity
If the stacking thickness of polyester textiles is increased, then the productivity is improved, but the decolorization uniformity deteriorates due to insufficient vapor penetration into the interior
Solution Approach 1:
The patent employs periodic steam injection and condensation cycles. Steam is injected, allowed to penetrate and condense, then condensed steam is removed and the process repeats. This periodic action creates repeated thermal cycles that progressively penetrate the textile stack, ensuring uniform decolorization throughout the thickness without compromising productivity.
Solution Approach 2:
The phase transition of water between vapor and liquid states during repeated cycles creates internal moisture gradients and temperature differences within the textile stack. These gradients drive continuous vapor penetration and heat transfer, ensuring uniform decolorization even at large stacking thicknesses.
3Strength
If the knitting density of polyester textiles is increased, then the fabric strength is improved, but the vapor diffusion resistance increases, leading to insufficient vapor contact
Solution Approach 1:
The patent maintains continuous steam exposure and moisture transfer throughout the decolorization process. The steam continuously penetrates the high-density fabric, and the moisture gradient is maintained throughout, ensuring that even tightly knitted fabrics receive sufficient vapor contact for complete decolorization without compromising fabric strength.
Solution Approach 2:
The thermal cycling causes expansion and contraction of the high-density knit structure, temporarily creating micro-channels that facilitate steam penetration through the tight fabric structure, thereby maintaining vapor diffusion ability despite high knitting density.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly enhances the decolorization rate and uniformity by allowing the vapor to fully contact the textiles, improving the decolorization process.
Implementation Method 1
the phase change material undergoes a phase change under the influence of a high temperature of the vapor of a decolorizing agent
Implementation Method 2
The phase change can create a local temperature difference within stacked polyester textile, thereby guiding the vapor of the decolorizing agent to penetrate the stacked polyester textiles
Implementation Method 3
heating a decolorizing agent to vapor for contact with the polyester textile to dissolve the dye
Data Source
AI summary
A method and a system for vapor-based decolorization of a polyester textile are provided. The method includes: obtaining a textile to be decolorized by adding a phase change material to the polyester textile for mixing, and performing the vapor-based decolorization on the textile to be decolorized. An amount of the phase change material corresponds to a weight of polyester in the polyester textile, and a phase change temperature of the phase change material is not greater than a vapor temperature of a decolorizing agent used in the vapor-based decolorization.